Normal tissue repair processes are critical for maintaining proper tissue function. Tissue fibrosis is characterized by the abnormal accumulation of extracellular matrix (“ECM”) that is thought to arise from unresolved tissue repair (Selman et al., “Idiopathic Pulmonary Fibrosis: Prevailing and Evolving Hypotheses About its Pathogenesis and Implications for Therapy,” Ann. Intern. Med. 134(2):136-151 (2001) and Mutsaers et al., “Mechanisms of Tissue Repair: From Wound Healing to Fibrosis,” Int. J. Biochem. Cell Biol. 29(1):5-17 (1997)). Fibrosis affects many organ systems, including the lung, kidney, liver and heart; and many disease processes, including cardiomyopathies, hypertension, chronic hepatitis C infection, adult respiratory distress syndrome, and sarcoidosis are accompanied by fibrosis (Pugin et al., “The Alveolar Space is the Site of Intense Inflammatory and Profibrotic Reactions in the Early Phase of Acute Respiratory Distress Syndrome,” Crit. Care Med. 27(2):304-312 (1999); Bedossa et al., “Liver Extracellular Matrix in Health and Disease,” J. Pathol. 200(4):504-515 (2003); Heling et al., “Increased Expression of Cytoskeletal, Linkage, and Extracellular Proteins in Failing Human Myocardium,” Circ. Res. 86(8):846-853 (2000); Intengan et al., “Vascular Remodeling in Hypertension: Roles of Apoptosis, Inflammation, and Fibrosis,” Hypertension. 38(3 Pt 2):581-587 (2001); and Berk et al., “ECM Remodeling in Hypertensive Heart Disease,” J. Clin. Invest. 117(3):568-575 (2007)). Current therapies to treat fibrotic conditions, including dermal fibrosis and liver fibrosis, have limited efficacy (Wolfram et al., Hypertrophic Scars and Keloids—A Review of Their Pathophysiology, Risk Factors, and Therapeutic Management,” Dermatol. Surg. 35(2):171-181 (2009); Butler et al., “Current Progress in Keloid Research and Treatment,” J. Am. Coll. Surg. 206(4):731-741 (2008); Muriel et al., “Beneficial Drugs for Liver Diseases,” J. Appl. Toxicol. 28:93-103 (2008); Kisseleva et al., “Recent Advances in Liver Stem Cell Therapy,” Curr. Opin. Gastroenterol. 26(4):395-402 (2010); and Thompson et al., “Antifibrotic Therapies: Will We Ever Get There?” Curr. Gastroenterol. Rep. 12:23-29 (2010)).
Tissue repair is a multi-step process that is initiated upon tissue injury and involves platelet activation, blood clotting, and the local release of inflammatory mediators and cytokines. Following injury, fibronectin is crosslinked into the fibrin clot (Hynes R., Fibronectins (Springer-Verlag 1990) and Colvin R., “Fibronectin in Wound Healing,” In Fibronectin (Mosher D. ed., 1989)), where it promotes the migration and attachment of fibroblasts, endothelial cells, monocytes and neutrophils (Hynes R., Fibronectins (Springer-Verlag 1990); Colvin R., “Fibronectin in Wound Healing,” In Fibronectin (Mosher D. ed., 1989); and Grinnell et al., “Fibroblast Adhesion to Fibrinogen and Fibrin Substrata: Requirement for Cold-Isoluble Globulin (Plasma Fibronectin),” Cell 19:517-525 (1980)). In later stages of tissue repair, the fibronectin-rich provisional matrix is replaced by granulation tissue, which is rich in collagen. Fibronectin matrix polymerization is required for deposition of collagen I fibrils (Sottile et al., “Fibronectin Polymerization Regulates the Composition and Stability of Extracellular Matrix Fibrils and Cell-Matrix Adhesions,” Mol. Biol. Cell. 13:3546-3559 (2002); Sottile et al., “Fibronectin-Dependent Collagen I Deposition Modulates the Cell Response to Fibronectin,” Am. J. Physiol. Cell Physiol. 293:C1934-1946 (2007); Velling et al., “Polymerization of Type I and III Collagens is Dependent on Fibronectin and Enhanced by Integrins alpha 11-beta 1 and alpha 2-beta 1,” J. Biol. Chem. 277(40):37377-37381 (2002); and McDonald et al., “Role of Fibronectin in Collagen Deposition: Fab′ to the Gelatin-Binding Domain of Fibronectin Inhibits both Fibronectin and Collagen Organization in Fibroblast Extracellular Matrix,” J. Cell. Biol. 92:485-492 (1982)). Contraction of myofibroblasts within the granulation tissue serves to reduce the area of the wound and to enhance the mechanical strength of regenerating tissue (Mutsaers et al., “Mechanisms of Tissue Repair: From Wound Healing to Fibrosis,” Int. J. Biochem. Cell Biol. 29(1):5-17 (1997)). Fibronectin matrix polymerization is an important regulator of cell growth, cell migration, cell contractility, and ECM remodeling (Sottile et al., “Fibronectin Polymerization Regulates the Composition and Stability of Extracellular Matrix Fibrils and Cell-Matrix Adhesions,” Mol. Biol. Cell. 13:3546-3559 (2002); Sottile et al., “Fibronectin-Dependent Collagen I Deposition Modulates the Cell Response to Fibronectin,” Am. J. Physiol. Cell Physiol. 293:C1934-1946 (2007); Hocking et al., “Stimulation of Integrin-Mediated Cell Contractility by Fibronectin Polymerization,” J. Biol. Chem. 275:10673-10682 (2000); Sottile et al., “Fibronectin Matrix Assembly Enhances Adhesion-Dependent Cell Growth,” J. Cell Sci. 111:2933-2943 (1998)), and as such, is an important regulator of tissue repair.
Many of the processes that occur in normal tissue repair also occur during fibrosis (Selman et al., “Idiopathic Pulmonary Fibrosis: Prevailing and Evolving Hypotheses About its Pathogenesis and Implications for Therapy,” Ann. Intern. Med. 134(2):136-151 (2001) and Mutsaers et al., “Mechanisms of Tissue Repair: From Wound Healing to Fibrosis,” Int. J. Biochem. Cell Biol. 29(1):5-17 (1997)). In fibrotic disorders, abnormal, excessive deposition of ECM leads to a disruption of normal tissue architecture and impaired organ function (Selman et al., “Idiopathic Pulmonary Fibrosis: Prevailing and Evolving Hypotheses About its Pathogenesis and Implications for Therapy,” Ann. Intern. Med. 134(2):136-151 (2001); Zeisberg et al., “Role of Fibroblast Activation in Inducing Interstitial Fibrosis,” J. Nephrol. 13 Suppl 3:S111-120 (2000); Fang, K C., “Mesenchymal Regulation of Alveolar Repair in Pulmonary Fibrosis,” Am. J. Respir. Cell Mol. Biol. 23(2):142-145 (2000)). Enhanced fibronectin and collagen deposition is associated with fibrotic diseases including interstitial pulmonary fibrosis (Selman et al., “Idiopathic Pulmonary Fibrosis: Prevailing and Evolving Hypotheses About its Pathogenesis and Implications for Therapy,” Ann. Intern. Med. 134(2):136-151 (2001); McDonald J., “Fibronectin In the Lung,” In Fibronectin (Mosher D. ed., 1989)); Demling R H., “The Modern Version of Adult Respiratory Distress Syndrome,” Ann. Rev. Med. 46:193-202 (1995); Gauldie et al., “TGF-β, Smad3 and the Process of Progressive Fibrosis,” Biochem. Soc. Trans. 35(Pt 4):661-664 (2007)), renal fibrosis (Zeisberg et al., “Role of Fibroblast Activation in Inducing Interstitial Fibrosis,” J. Nephrol. 13 Suppl 3:S111-120 (2000)), dermal fibrosis (Singer et al., “Cutaneous Wound Healing,” N. Engl. J. Med. 341(10):738-746 (1999); Wolfram et al., Hypertrophic Scars and Keloids—A Review of Their Pathophysiology, Risk Factors, and Therapeutic Management,” Dermatol. Surg. 35(2):171-181 (2009); Kischer et al., “Fibronectin (FN) in Hypertrophic Scars and Keloids,” Cell Tissue Res. 231(1):29-37 (1983); Kischer et al., “Increased Fibronectin Production by Cell Lines from Hypertrophic Scar and Keloid,” Connect. Tissue Res. 23(4):279-288 (1989)), liver fibrosis (Brenner, D. A., “Molecular Pathogenesis of Liver Fibrosis,” Trans. Am. Clin. Climatol. Assoc. 120:361-368 (2009); Friedman, S. L., “Hepatic Stellate Cells: Protean, Multifunctional, and Enigmatic Cells of the Liver,” Physiol. Rev. 88:125-172 (2008); Bedossa et al., “Liver Extracellular Matrix in Health and Disease,” J. Pathol 200:504-515 (2003)), and cardiac fibrosis (Heling et al., “Increased Expression of Cytoskeletal, Linkage, and Extracellular Proteins in Failing Human Myocardium,” Circ. Res. 86(8):846-853 (2000); van Dijk et al., “Accumulation of Fibronectin in the Heart after Myocardial Infarction: A Putative Stimulator of Adhesion and Proliferation of Adipose-Derived Stem Cells,” Cell Tissue Res. 332(2):289-298 (2008); Tsutsumi et al., “Angiotensin II Type 2 Receptor is Upregulated in Human Heart with Interstitial Fibrosis, and Cardiac Fibroblasts are the Major Cell Type for its Expression,” Circ. Res. 83(10):1035-1046 (1998)). Persistent fibroblast “activation” is thought to lead to continued fibroblast proliferation, excessive ECM production, and aberrant ECM remodeling. The underlying cause of this fibroblast “activation” is unknown, but may result from chronic inflammation, abnormal fibroblast response to growth factors, altered cell response to ECM, an altered balance of matrix degradation and deposition, and/or aberrant interactions between epithelial and mesenchymal cells (Selman et al., “Idiopathic Pulmonary Fibrosis: Prevailing and Evolving Hypotheses About its Pathogenesis and Implications for Therapy,” Ann. Intern. Med. 134(2):136-151 (2001); Butler et al., “Current Progress in Keloid Research and Treatment,” J. Am. Coll. Surg. 206(4):731-741 (2008); Zeisberg et al., “Role of Fibroblast Activation in Inducing Interstitial Fibrosis,” J. Nephrol. 13 Suppl 3:S111-120 (2000); Gauldie et al., “TGF-β, Smad3 and the Process of Progressive Fibrosis,” Biochem. Soc. Trans. 35(Pt 4):661-664 (2007); Eckes et al., “Fibroblast-Matrix Interactions in Wound Healing and Fibrosis,” Matrix Biol. 19(4):325-332 (2000)).
While modulation of fibronectin deposition and ECM formation has been demonstrated in vitro, the ability to control fibronectin deposition and ECM formation in vivo and the therapeutic utility of doing so remains elusive. The reason for this is that, as noted above, fibronectin deposition and ECM formation is necessary for normal function. Indeed, fibronectin knockout mice and collagen I knockout mice both die in utero (Lohler et al., “Embryonic Lethal Mutation in Mouse Collagen I Gene Causes Rupture of Blood Vessels and is Associated with Erthropoietic and Mesenchymal Cell Death,” Cell 38:597-607 (1984); George et al., “Defects in Mesoderm, Neural Tube, and Vascular Development in Mouse Embryos Lacking Fibronectin,” Dev. 119:1079-1091 (1993); and George et al., “Fibronectins are Essential for Heart and Blood Vessel Morphogenesis But are Dispersible for Initial Specification of Precursor Cells,” Blood 90(8):3073-3081), suggesting that modification of fibronectin deposition and ECM formation processes can have unintentional and undesirable consequences. It would be desirable to identify an approach for treating fibrosis, particularly cardiac, pulmonary, liver, and/or dermal fibrosis, that offers improvement over current therapies.
The present invention is directed to overcoming these and other deficiencies in the art.